Hi,
Your server is making the web server the owner when it installs the template, this is common with joomla when installing modules and templates. There are loads of forum posts that explain this also I think there is something on joomla.org.
The easiest way to overcome this - mainly because the cpanel and ftp clients dont work is to install a component called Joomlaxplorer that allows you to browse to the template folders and change the permissions.
http://extensions.joomla.org/component/option,com_mtree/task,viewlink/link_id,102/Itemid,35/
I hope this helps,